A radiation system (e.g., a computed tomography (CT) scanner, a radiotherapy apparatus) may include a collimation assembly to reduce harmful radiation emitted from a radiation source. Application specific adjustments to the radiation reduction is achieved using the physical movement of a collimator device within the collimation assembly. The movement of the collimator device may be actuated and/or guided by a motion system. However, a traditional motion system typically has unintentional over constraints leading to unpredictable performance from varying friction over the lifetime of the system. Therefore, it is desirable to develop a friction free motion guidance assembly for guiding the movement of the collimator device.